A10-year-old male child complains of pain and swelling in the left foot. He gives a history of injury while playing. Migration of leukocytes to the site of injury is mediated by
**Core Concept**
Inflammation is a complex biological response to tissue injury, characterized by the migration of leukocytes to the site of injury. This process is mediated by various chemical signals and molecular pathways.
**Why the Correct Answer is Right**
The migration of leukocytes to the site of injury is primarily mediated by chemokines, which are a family of small cytokines that induce directed chemotaxis in nearby responsive cells. Chemokines interact with specific receptors on the surface of leukocytes, triggering a signaling cascade that leads to the activation and migration of these cells to the site of injury. In this context, chemokine receptors, such as CXCR1 and CXCR2, play a crucial role in the recruitment of neutrophils to the site of injury.
**Why Each Wrong Option is Incorrect**
**Option A:** Interleukins (ILs) are a group of cytokines that play a role in regulating the immune response, but they are not directly responsible for the migration of leukocytes to the site of injury.
**Option B:** Tumor necrosis factor-alpha (TNF-alpha) is a cytokine that plays a role in systemic inflammation and is involved in the regulation of immune cells, but it is not the primary mediator of leukocyte migration to the site of injury.
**Option C:** Adhesion molecules, such as selectins and integrins, play a critical role in the adhesion and transmigration of leukocytes across the endothelium, but they are not the primary mediators of leukocyte migration to the site of injury.
**Clinical Pearl / High-Yield Fact**
Chemokines are a family of small cytokines that play a critical role in the recruitment of immune cells to sites of injury or infection. Understanding the chemokine receptors and their ligands is essential for appreciating the complex mechanisms underlying inflammation and immune responses.
**Correct Answer: C. Adhesion molecules, such as selectins and integrins, play a critical role in the adhesion and transmigration of leukocytes across the endothelium, but they are not the primary mediators of leukocyte migration to the site of injury.